Cu—Fe—P alloys which contain Fe and P have been commonly employed in the past as copper alloys in the various applications described above, beginning with semiconductor IC lead frames and the like. Examples of such Cu—Fe—P alloys include copper alloys that contain 0.05 to 0.15% Fe and 0.025 to 0.040% P (C19210 alloy) and copper alloys that contain 2.1 to 2.6% Fe, 0.015 to 0.15% P and 0.05 to 0.20% Zn (CDA194 alloy). If Fe or an inter-metallic compound such as Fe—P or the like is precipitated in a copper matrix phase, such Cu—Fe—P alloys are superior even among copper alloys in terms of strength, electrical conductivity and thermal conductivity; accordingly, these alloys are commonly used as international standard alloys.
In recent years, with the expanded use of Cu—Fe—P alloys, and the reduced weight, increased thinness and more compact size of electrical and electronic devices, there has been a demand for even greater strength and conductivity, and superior bending workability, in these copper alloys as well. In regard to such bending workability, there has been a demand for characteristics that allow severe bending such as U-bending, 90-degree bending after notching and the like.
In regard to these requirements, it has long been known that the bending workability can be improved to some extent by making the crystal grains finer, or by controlling the disperse state of the crystallized/precipitated matter (see patent documents 1-6 below).
Furthermore, in the case of Cu—Fe—P alloys, control of the aggregate structure has also been proposed as a means of improving various characteristics such as bending workability and the like. In more concrete terms, it has been proposed that the ratio of the X-ray diffraction intensity I(200) of the plane (200) to the X-ray diffraction intensity I(220) of the plane (220) in copper alloy plates, i.e., I(200)/I(220), be 0.5 to 10, that the orientation density of the cubic orientation, i.e., D(cubic orientation), be 1 to 50, or that the ratio of the orientation density D(cubic orientation) of the cubic orientation to the orientation density D(S orientation) of the S orientation, i.e., D(cubic orientation)/D(S orientation), be 0.1 to 5 (see patent document 7 below).
Furthermore, it has been proposed that the ratio of the sum of the X-ray diffraction intensity I(200) of the plane (200) and the X-ray diffraction intensity I(311) of the plane (311) to the X-ray diffraction intensity I(220) of the plane (220) in copper alloy plates, i.e., [I(200)+I(311)]/I(220), be 0.4 or greater (see patent document 8 below).
Patent document 1: Japanese Patent Application Laid-Open No. 6-235035 (entire text)
Patent document 2: Japanese Patent Application Laid-Open No. 2001-279347 (entire text)
Patent document 3: Japanese Patent Application Laid-Open No. 2005-133185 (entire text)
Patent document 4: Japanese Patent Application Laid-Open No. 10-265873 (entire text)
Patent document 5: Japanese Patent Application Laid-Open No. 2000-104131 (entire text)
Patent document 6: Japanese Patent Application Laid-Open No. 2005-133186 (entire text)
Patent document 7: Japanese Patent Application Laid-Open No. 2002-339028 (paragraphs 0020 to 0030)
Patent document 8: Japanese Patent Application Laid-Open No. 2000-328157 (embodiments)